Fix bug #11133 with vertical-motion across a long display string.

 src/indent.c (Fvertical_motion): If there is a display string at
 point, use it.vpos to compute how many lines to backtrack after 
 move_it_to point.

2 files changed, 19 insertions, 1 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index af65d38a33b..6bd946c0900 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,9 @@
+2012-04-07  Eli Zaretskii  <eliz@gnu.org>
+
+        * indent.c (Fvertical_motion): If there is a display string at
+        point, use it.vpos to compute how many lines to backtrack after
+        move_it_to point.  (Bug#11133)
+
 2012-04-06  Eli Zaretskii  <eliz@gnu.org>
 
         * buffer.h (FETCH_CHAR, FETCH_MULTIBYTE_CHAR):
diff --git a/src/indent.c b/src/indent.c
index a1fcd2b1018..9b4279f0c4e 100644
--- a/src/indent.c
+++ b/src/indent.c
@@ -2021,6 +2021,7 @@ whether or not it is currently displayed in some window.  */)
       EMACS_INT it_start;
       int first_x, it_overshoot_count = 0;
       int overshoot_handled = 0;
+      int disp_string_at_start_p = 0;
 
       itdata = bidi_shelve_cache ();
       SET_TEXT_POS (pt, PT, PT_BYTE);
@@ -2035,6 +2036,8 @@ whether or not it is currently displayed in some window.  */)
         {
           const char *s = SSDATA (it.string);
           const char *e = s + SBYTES (it.string);
+
+          disp_string_at_start_p = it.string_from_display_prop_p;
           while (s < e)
             {
               if (*s++ == '\n')
@@ -2062,7 +2065,8 @@ whether or not it is currently displayed in some window.  */)
       /* IT may move too far if truncate-lines is on and PT lies
          beyond the right margin.  IT may also move too far if the
          starting point is on a Lisp string that has embedded
-         newlines.  In these cases, backtrack.  */
+         newlines, or spans several screen lines.  In these cases,
+         backtrack.  */
       if (IT_CHARPOS (it) > it_start)
         {
           /* We need to backtrack also if the Lisp string contains no
@@ -2073,6 +2077,14 @@ whether or not it is currently displayed in some window.  */)
               && it.method == GET_FROM_BUFFER
               && it.c == '\n')
             it_overshoot_count = 1;
+          else if (disp_string_at_start_p && it.vpos > 0)
+            {
+              /* This is the case of a display string that spans
+                 several screen lines.  In that case, we end up at the
+                 end of the string, and it.vpos tells us how many
+                 screen lines we need to backtrack.  */
+              it_overshoot_count = it.vpos;
+            }
           if (it_overshoot_count > 0)
             move_it_by_lines (&it, -it_overshoot_count);